Anaxagoras

Quick Facts

• Name: Anaxagoras
• Lived: c. 500-c. 428 BCE
• From: Clazomenae in Ionia, on the coast of Asia Minor
• Worked in: Athens, then Lampsacus after exile
• Tradition: Presocratic philosophy and natural philosophy
• Main work: one lost prose book, usually called On Nature
• Best known for: Nous, mixture, "everything in everything," and natural explanations of the heavens

The Big Question

How can the world really change if nothing can come from nothing?

Parmenides had argued that what is cannot come from what is not, and cannot pass away into what is not. Anaxagoras accepted that challenge. He did not answer by denying the everyday world of eating, growing, weather, birth, and death. He answered by saying that change is not creation or destruction. Change is mixing, separating, and rearranging what was already there.

In One Minute

Anaxagoras was a Greek Presocratic thinker who helped bring Ionian natural philosophy to Athens. He tried to explain nature without turning every hard question into a story about the gods.

His central idea is that every ordinary thing is a mixture. Nothing appears from nothing. Bread can become flesh, blood, bone, and hair because the materials needed for those things are already present in the food in tiny, hidden amounts. A thing looks like one kind of thing because one ingredient is dominant in it.

He also introduced Nous, meaning Mind or Intelligence, as the ordering power of the cosmos. In the beginning, all things were mixed together. Nous began a rotating motion that sorted the mixture into the ordered world.

What They Taught

Anaxagoras taught that nature is made from an unlimited mixture of ingredients. These ingredients are not created and destroyed. They combine, separate, thicken, thin out, and change their balance.

This solves a problem left by Parmenides. If nothing comes from nothing, then flesh cannot simply come into being from bread as if bread vanished and flesh appeared by magic. Anaxagoras says the bread already contains portions of flesh, blood, bone, hair, and many other stuffs. Eating does not create flesh from non-flesh. It separates and gathers what was already present.

This is the meaning of his famous claim that everything is in everything. It does not mean that a tiny horse is inside every grain of wheat. It means that every portion of ordinary matter contains many kinds of ingredient. Most of them are too small, too weak, or too mixed in to be visible. What we see depends on what predominates. Predominance means "having the greatest share or strongest presence." Snow looks white because white predominates. Salt tastes salty because the salty ingredient is strong enough to show itself.

Anaxagoras also taught that the first cosmic state was a vast mixture in which all things were together. There was no empty space filled with finished objects. There was a dense blend of stuffs. Then Nous began rotation. This whirl separated and arranged ingredients: bright and hot moved one way, dense and cold another way, and earth, sky, sun, moon, stars, animals, and plants emerged from the sorting.

Nous is Mind, Intelligence, or ordering power. It is not just another ingredient like bone or fire. Anaxagoras describes it as pure, independent, and able to know and rule. It starts motion and orders what the mixture becomes. Still, he does not make Nous a personal creator who designs every detail for the best. Later philosophers noticed this. They admired the idea of Mind but complained that Anaxagoras often explained particular events by physical causes rather than by purpose.

His astronomy followed the same natural style. The sun was not a god driving across the sky. It was a fiery stone. The moon did not shine by itself; it received light from the sun. Eclipses happened when one body blocked light from another. These claims were not modern science, but they were a major step toward treating the heavens as part of nature.

Key Ideas With Examples

• Nous: Mind or Intelligence. It begins the cosmic rotation and orders the mixture. Example: imagine a bowl of thick mixed paint. Nous is not one more color in the bowl. It is the power that starts the stirring pattern by which some colors become more visible in different places.

• Mixture: the basic condition of matter. A mixture is a blend in which many ingredients are present together. Example: food seems to become muscle and bone after digestion. Anaxagoras says the food already had hidden portions of the stuffs that become muscle and bone.

• Seeds or ingredients: the basic stuffs present in things. Ancient and modern writers often call them "seeds," but Anaxagoras' idea is broader than plant seeds. They are the natural stuffs that can become dominant in a mixture, such as hot, cold, bright, dark, flesh, bone, and blood.

• Everything in everything: every portion of matter contains a share of every kind of ingredient. Example: even sweet water contains some salty ingredient, though it is too weak to taste. If salty stuff becomes dominant, the water tastes salty.

• Predominance: the ingredient with the strongest presence gives a thing its visible character. Example: a loaf of bread is called bread because bread-like qualities dominate, not because every other ingredient is absent.

• No smallest piece: there is no final, pure grain of matter with only one ingredient in it. However far you divide something, Anaxagoras thinks it still contains many ingredients. This helps him say that everything remains mixed with everything.

• No absolute birth or destruction: coming-to-be and passing-away are really mixing and separating. Example: a plant growing from soil and water is not new being from nothing. It is an arrangement of already existing ingredients into a living form.

• Natural explanation: explaining strange events by causes inside nature. Example: an eclipse is not mainly an omen. It happens when the moon, earth, or another body blocks light.

• Cosmology: an account of how the ordered universe formed. Anaxagoras' cosmology begins with the total mixture, then explains the world by rotation, separation, and the ordering activity of Nous.

Major Works

• On Nature: the usual later title for Anaxagoras' lost book. Only fragments and ancient reports survive, especially through later writers such as Simplicius and Aristotle. The work seems to have opened with the claim that all things were together. It explained the world as a mixture ordered by Nous and developed the doctrines of mixture, separation, and "everything in everything."

Why It Matters

Anaxagoras matters because he gives one of the strongest early answers to Parmenides. He keeps the rule that nothing comes from nothing, but he still explains a changing world. Growth, digestion, weather, astronomy, birth, and death become processes of mixture and separation.

He also matters because of Nous. The idea that Mind has a cosmic role shaped later debates about order, cause, intelligence, and purpose. Even when Plato and Aristotle criticized him, they treated him as someone who had seen an important problem.

His natural explanations of the sun, moon, stars, eclipses, meteorites, and weather also made him important for the history of science. Some claims were wrong. The larger move was powerful: heavenly events could be investigated as natural events.

Proponents, Critics, and Opponents

Anaxagoras belongs with the Presocratics, especially the pluralists. Pluralists thought reality must contain many basic things, not just one. Empedocles used four roots, earth, air, fire, and water, moved by Love and Strife. Anaxagoras used countless ingredients ordered by Nous.

He is also part of the post-Parmenidean debate. Parmenides forced later thinkers to explain how change can be real without letting being come from non-being. Anaxagoras' answer was mixture. The atomists, especially Democritus, offered a different answer: indivisible atoms moving in empty space.

Socrates, as Plato presents him, was excited by Anaxagoras' claim that Mind orders all things. He hoped this would explain why things are arranged for the best. He was disappointed when Anaxagoras mostly used air, aether, meaning the fiery upper region, water, and other physical causes instead of showing purposes.

Plato and Aristotle made similar criticisms. Aristotle praised Anaxagoras for introducing Mind as a cause, but thought he used it too rarely, almost as a backup when ordinary physical explanation failed.

His Athenian career also brought political and religious danger. Ancient sources say he was accused of impiety, meaning disrespect toward the gods, partly because he treated the sun and moon as natural bodies rather than divine beings. His connection with Pericles probably made the charge more dangerous. He left Athens and died in Lampsacus.

Related Pages

• Presocratics
• Natural Philosophy
• Parmenides
• Empedocles
• Democritus
• Socrates
• Plato
• Aristotle